Nun galilaeus has the elongated, subcylindrical body shape typical of stone loaches with its mean depth being 15.5% of its length.

The dorsal fin has a slightly convex to near straight upper margin and 4-5 unbranched and 9-11 branched rays.

The body is scaleless and the lateral line extends to the anal fin.

The body colour is generally a light yellowish brown with an irregular pattern of grey brown mottles and a varying number of diffuse bars or blotches which can fuse towards the caudal fin for vertical stripes.

[1] It can also be found in very slow flowing, almost stagnant water in the tributaries to Lake Muzairib where it lives among stones and the roots of willows.